1. Field of the Invention
The present invention relates generally to a so-called "auto-aircon", i.e. an air conditioner for automobiles, and more particularly to a control apparatus for producing control data based on various control factors for the control of components of the automobile air-conditioner.
2. Description of the Prior Art
A conventional system for controlling an air-mix door of an automobile air-conditioner is known as disclosed, for, example, in Japanese Patent Publication No. 59-39334. The known control system includes, as reillustrated here in FIG. 7 of the accompanying drawings, a temperature setter 21 for setting a desired temperature T.sub.D, a vehicle compartment temperature sensor 22 for detecting the temperature T.sub.R in a vehicle compartment, an outside air temperature sensor 23 for detecting the temperature T.sub.A of air outside the vehicle compartment, and a position sensor 24 for detecting the position X.sub.P of an air-mix door 12. Pieces of data detected by the respective sensors 21-24 are inputted, as control factors, into an A/D converter 27 which in turn converts the inputted analog signals into digital signals T.sub.D, T.sub.R, T.sub.A and X.sub.P. Then, predetermined gains A, B, C and D are added to the respective digital signals T.sub.D, T.sub.R, T.sub.A and X.sub.P to thereby obtain A.multidot.T.sub.D, B.multidot.T.sub.R, C.multidot.T.sub.A and D.multidot.X.sub.P. The thus obtained B.multidot.T.sub.R, C.multidot.T.sub.A and D.multidot.X.sub.P are added together to obtain a composite parameter K1 according to the following equation. EQU K1=B.multidot.T.sub.R +C.multidot.T.sub.A +D.multidot.X.sub.P +F
where F is a correction coefficient. Thereafter, the composite parameter K1 and the A.multidot.T.sub.D are used to calculate control data for controlling the operation of the air-mix door 12. The control data is supplied to a control unit or means 100 which control the position of the air-mix door 12 according to the control data.
If the first and second terms of the right member of the above-mentioned equation is substituted by X.sub.M2, then X.sub.M2 is indicated by the following equation. EQU X.sub.M2 =B.multidot.T.sub.R +C.multidot.T.sub.A
When this equation is indicated by a graph whose Y-axis and X-axis are taken with respect to X.sub.M2 and T.sub.R, respectively, then it is represented by a group of straight lines having a constant gradient B and different intercepts varying with T.sub.A, as shown in FIG. 8.
However, an experiment uncovered the fact that optimum composite parameters X.sub.M2 obtained based on T.sub.R and T.sub.A on the basis of the bodily sensation of an occupant are not indicated by a group of straight lines. This means that the control data obtained by the first-mentioned equation is incapable of realizing a fine control of the air-conditioner needed for providing a sense of comfort for the occupant which varies with various temperature conditions of air inside and outside the vehicle compartment.
With the foregoing drawbacks in view, it may be proposed a control system in which various values for X.sub.M2 are experimentally obtained by all of the possible values of T.sub.R and T.sub.A and the thus-obtained X.sub.M2 values are stored as map data in a memory device; when a value of T.sub.R and a value of T.sub.A are inputted, then a corresponding X.sub.M2 value is read out from the memory device for controlling operation of the air-conditioner. This control system, however, requires a large number of groups of map data and hence a great memory capacity. If the number of groups of map data were reduced for saving the memory capacity, a corresponding reduction of control accuracy would result.